Differential input stages are used in various types of analog integrated circuits and for various applications. Such input stages may, for instance, be used to form operational amplifiers. Differential input stages typically include a tail current source that supplies current to multiple transistors. The flow of current through the transistors is controlled by input voltages that are applied to the transistors. The differential input stage may thus be characterized by a transconductance—that is, the response of the current output by the differential input stage as a function of the input voltages provided to the differential input stage. Many differential input stages provide stable transconductance when the input voltages are within a narrow, defined range.